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Table of Contents: 2020 SEPTEMBER–OCTOBER No. 436

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NLM Classification 2020 Summer Edition Now Available

Willis, S. NLM Classification 2020 Summer Edition Now Available. NLM Tech Bull. 2020 Sep-Oct;(436):e4.

2020 September 30 [posted]

NLM Classification Redesign

Beginning with the 2020 summer edition, the NLM Classification has a new look and feel. With this new design comes a new URL ( The old URL ( will automatically be redirected to the new one. The new site functions best in Chrome or Firefox.

New NLM Classification Interface
Figure 1: New NLM Classification Interface.

New features

The look may be different, but the organization structure of schedules and index pages remains the same. Some new features include:

  • No search boxes on the home page. Users can access searches of the schedules via the navigation bar at the top right corner.
  • Links to documentation have been rearranged and updated.
  • Users are able to refine searches by choosing a search type:
    • Exact – search for word(s)/class number(s) in exact order
    • Contains – search for words that appear in relative proximity
    • Startswith – search for word(s)/class number(s) that begins with search term
  • Schedule range headers are displayed on the left side of the schedule page rather than at the top.
  • Index entries are displayed in a collapsed form. Where applicable, the user must click on the plus sign to expand and view the entire index entry.

For more details see the Help Instructions for the NLM Classification Public Pages.


Scope of Revision of the 2020 Summer Edition

The major focus of the 2020 summer edition was the systematic review of the following schedules: WD (Disorders of Systemic, Metabolic or Environmental Origin, etc.) and WO (Surgery). In addition to the systematic reviews of the WD and WO schedules, other minor additions and changes were made.


Summary Statistics for the 2020 Summer Edition

  • 132 class numbers added
  • 8 schedule range headers added
  • 171 class number captions or notes modified
  • 119 schedule range headers modified
  • 74 class numbers canceled
  • 9 schedule range headers deleted
  • 49 index main headings added
  • 763 index entries modified
  • 50 index headings deleted


Systematic Reviews for the 2020 Summer Edition

Highlights from the WD (Disorders of Systemic, Metabolic or Environmental Origin, etc.)

A partial review of the WD schedule was already conducted with the 2019 summer edition systematic review to consolidate certain subjects in the QW and other schedules. The review of the rest of the WD schedule was completed with the 2020 summer edition. As a result, the following changes were made:

  • The WD Schedule Header was changed from Disorders of Systemic, Metabolic or Environmental Origin, etc. to Medicine in Selected Environments.
  • WD 100-175 Nutrition Disorders cancelled:
    • New section created in QU schedule for Nutrition Disorders: QU 242-252
    • Malnutrition QU 244 and Obesity QU 248 given Table G breakdown
    • General Deficiency Diseases moved from WD 105 to QU 246
    • Vitamin deficiencies WD 110-155 are now classed with the actual vitamins
    • Vitamins QU 167-181 separated from Nutrition header in the QU schedule and made an independent section
    • Celiac Disease. Sprue moved from WD 175 to the new number WI 471, indented under the new number WI 470 Malabsorption syndromes (formerly WD 200.5.M2)
  • WD 200-205 Metabolic Diseases New section created in QU schedule for Metabolic Diseases: QU 260 A-Z; QU 265 A-Z for Inborn Errors of Metabolism.
  • WD 220-226 Water-Electrolyte Imbalance New section created for Water-Electrolyte Imbalance. Acid-Base Imbalance. Two separate class numbers were created for the two imbalances: QU 270 and QU 274. Works on regular balance are classified in QU 105.
  • WD 300-380 Connective Tissue Diseases (Note: Several numbers in the WD 300-330 Immune System Related Diseases area had already been cancelled with 2019 summer edition.) Connective Tissue Diseases and Collagen Diseases moved to new section: QZ 192-196.
  • WD 600-670 Disorders and Injuries of Environmental Origin
    • WD 600 Persian Gulf Syndrome moved to new number QZ 146 Syndromes
    • WD 602 Electric Injuries and WD 670 Cold Injuries moved to WO schedule
    • Several revisions made to QT 162 area:
      • Many disorders moved from WD to QT 162 with Environmental factors acting on human physiology, e.g., Motion Sickness classed with Motion
      • 4 new QT 162 A-Z numbers created; 1 number cancelled; 2 numbers modified
    • WD 650 Submarine medicine moved to new number under Naval Medicine section
  • WB 107 Wilderness Medicine New section header and one number created: WD 680
  • WD 700-745 header broadened: changed from Aviation Medicine to Aerospace Medicine. Other changes in this section:
    • 8 new form numbers created in this area based on literary warrant
    • 6 existing captions or notes modified
    • 1 number cancelled: WD 745 Aviation dentistry
  • WD 750-760 header changed from Space Medicine to Space Flight
  • WD 800 Naval Medicine section enhanced:
    • 27 new form numbers created based on literary warrant
    • New numbers created for Submarine Medicine WD 850-860 in Naval Medicine section
    • New number created for Collective Biography of Naval Personnel WZ 112.5.N2
  • WB 116 Military Medicine New section created for Military Medicine at WD 900
    • 35 new form numbers created
    • Naval medicine schools are classed in WD 919 with Military Medicine

Highlights from the WO (Surgery)

  • The WO Schedule Header was changed from Surgery to Wounds and Injuries
  • 14 New WO numbers created
WO 320 Nerve block
WO 502 Surgical hemostasis
WO 504 Electrosurgery
WO 508 Ablation techniques
WO 595 Cosmetic techniques
WO 662 Tissue and organ procurement. Tissue donors
WO 664 Cell- and tissue-based therapy (works on stem cell transplantation classed in QU 325)
WO 705 Cold injury
WO 720 Asphyxia
WO 730 Multiple trauma
WO 750 Emergency Surgery
WO 780 War-related injuries (General)
WO 810 Stab wounds
WO 840 Electric injuries
  • 8 WO numbers cancelled
WO 140 Surgical diseases (General) (Classify general works on prognosis and treatment of surgical diseases in WO 500. Classify works on surgery for specific diseases with the disease)
WO 198 Electrosurgery. Cautery. Laser and electrocoagulation (General) (Classify works on cautery in WO 508. Classify works on electrosurgery in WO 504. Classify works on laser coagulation in WO 511)
WO 250 Asphyxia. Methods of resuscitation (Classify general works on asphyxia in WO 720. Classify works on resuscitation in WB 106 [new number]. Classify works on respiration problems caused by anesthesia in WO 245)
WO 290 Rectal (Classify works on rectal anesthesia in WO 275)
WO 297 Muscle relaxants and tranquilizing agents in conjunction with anesthesia and analgesia (Classify works on muscle relaxants in QV 140. Classify works on tranquilizing agents in QV 77.9)
WO 375 Diagnostic and therapeutic anesthetic procedures (Classify works on nerve block in WO 320 [new number]. Classify works on anesthetics in QV 81)
WO 515 Regenerative medicine (Classify works on regenerative medicine in QT 110)
WO 640 Prosthesis in plastic surgery (Classify works on surgically inserted prostheses and implants in WO 162)
  • 38 WO class number or notes were modified


Other 2020 Summer Edition Changes

Examples of additional changes made:

Classification of Specific Types of Diet

An analysis of diet terms was done by exploring the MeSH trees for Diet and Diet Therapy because not all the terms are in both trees. Decision: All Diet Therapy terms should point to WB. Terms that just tree under Diet can point to QT.

2 new numbers created:

  • WB 415 Caloric restriction. Reducing diet 
  • WB 423 Mediterranean diet

2 numbers modified

  • WB 425: Fat control. Dietary fats: Note adjusted to change WD class number to new WB 415 number: Classify works on weight reduction diets in WB 415
  • WB 431: Gluten-free diet added to caption

10 new index terms added:

  • Diet, Carbohydrate Loading -- WB 427
  • Diet, Gluten-Free -- WB 431
  • Diet, Healthy -- QT 235
  • Diet, High-Fat -- QT 235
  • Diet, High-Protein Low-Carbohydrate -- WB 427
  • Diet, Paleolithic -- WB 400
  • Diet, Western -- QT 235
  • Dietary Approaches To Stop Hypertension -- WG 340
  • Portion Size -- QT 235
  • Serving Size -- QU 145.3

Classification of Safety in Clinical Laboratories

QY 70 was expanded to include administrative aspects of clinical laboratories including standards. A new number, QY 75 Laboratory Safety, was created specifically for safety in laboratories. Several index terms were modified to add sub-indexes about safety and administrative aspects. New term added to index: Laboratory Proficiency Testing.

Classification of Renal Elimination

Caption at WJ 303 was changed from Urinary Secretion. Anuria (General) to Diuresis. Renal elimination. Renal Elimination was added to index to point to WJ 303.

W1 versus WY for Reports of Societies

Reports of an administrative nature, regardless of how often they are issued, should be classed with the society. Edits were made to notes across all the schedules at form number 1.



The PDF version of the NLM Classification will be updated with 2020 winter and summer classification data in late fall 2020.

The NLM Classification poster has been revised with 2020 data. The 18" x 24" poster will be available for ordering in late fall 2020. To order, please contact the NLM Communications Team. An 8.5" x 11" high resolution version of the 2020 poster is available in PDF at

The 2021 winter online edition will be published in late January 2021. It will encompass the additions and changes from the 2021 MeSH (Medical Subject Headings) vocabulary as evaluated for inclusion in the Classification index. All main index headings will be linked to the 2021 vocabulary in the MeSH Browser.

By Sharon R. Willis
Cataloging and Metadata Management Section, Technical Services Division

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